Water treatment systems are commonly used in water supply systems. In a residential water supply system, for example, water softeners, acid neutralizers, iron/manganese removal systems, arsenic removal systems, and aeration systems may be used to filter or treat the water being supplied from a water source (e.g., from a well or city water supply). To facilitate the removal of contaminants, such as iron, manganese, and sulfur, some water treatment systems aerate the water to provide oxidation prior to the filtering. In such systems, a head of air may be maintained at the top of a water treatment tank such that the water provided to the tank passes through the head of air before passing through filter media.
Some existing water treatment systems include a control valve (e.g., connected to the top of the tank) to control the water passing in to and out of the system according to water treatment operating cycles. To provide the head of air in an existing water treatment system that uses aeration, the control valve may perform an air charge cycle by directing water through a venturi coupled to an air inlet such that the venturi draws air into the top of the filter tank. During a service cycle, the control valve directs the water to flow through the trapped air in the tank, through filter media in the tank, and then to a service water system (e.g., a residential water system). The old compressed air in the tank may be released or discharged when the control cycle opens a drain line during a backwash cycle.
The use of these existing water treatment systems providing aeration presents several drawbacks. One such drawback is the noise and rattling of the drain line when the compressed air charge is released suddenly during the backwash cycle. If the drain line is not properly secured, this may also cause unwanted splashing, breaks and/or flooding. The rapid air escape may also cause the filter media to jump vertically inside the filter tank, causing it to be lost through the drain line and possibly causing plugging of the drain and flooding. To avoid this, existing systems often use less filter media and approximately 25% of the filter bed depth may be lost, requiring more frequent air regenerations, wasted water and wasted electricity. Using a larger tank results in more water going to drain during an air charge cycle and an increased cost of the filter media.
A further drawback of the existing systems providing aeration is the need for a backwash cycle before an air charge cycle to provide a new charge of air. These existing systems may not be recharged with air while remaining in service and the additional backwash cycles waste water.